Active RFID (radio frequency identification) tags, such as WiFi RFID tags, are employed in many applications. For example RFID tags can be used for asset tracking or location determination. For example, in a hospital RFID tags can be used to enable medical personnel to locate equipment such as heart monitors or defibrillators.
Some RFID tags announce their presence periodically by sending a multicast packet, such as a layer 2, 802.11 multicast packet, to a network without associating to an access point (AP). This is commonly referred to as announce mode. The AP is setup to allow packets to the known multicast address to be forwarded to a controller or other device on the network. Often it is desirable to provide secure communications for active Radio Frequency Identification (RFID) tags. For example, a secured announcement is an announcement encrypted with a key. However, there are several considerations for providing secure RFID communications. For instance, RFID tags have a limited battery life, which can limit what can be transmitted. Also, to preserve battery life, RFID tags have limited computational power, which can limit the complexity of the encryption algorithm employed by the tag.